1. Field of the Invention
The present invention relates to an apparatus for cleaning the conveyor chuck which carries a plurality of plate-like substrates such as semiconductor wafers to be processed while holding them together.
2. Description of the Related Art
The cleaning system has been used to remove particles, organic contaminating matters and metal impurities from surfaces of the semiconductor wafers in the course of manufacturing semiconductor devices. This cleaning system, particularly the wet cleaning system has been widely used as an important measure to effectively remove particles from the wafers in a batch. Usually, it comprises a loader unit into which plural carriers each housing a predetermined number of wafers therein are carried, conveyor robots each picking up and conveying a predetermined number of wafers from the carriers which have been loaded by the loader unit, plural cleaning sections arranged in a line to process the wafers carried as a batch with alkali, water and acid, and an unloader unit for unloading the wafers which have been cleaned in the cleaning sections.
When the wafers are to be cleaned, they are held by the wafer chuck of the conveyor robot and transferred into and out of process vessels in the cleaning sections. When the wafer chuck comes together with the wafers into and out of the process vessels in this manner, washing solutions or agents in the process vessels adhere to the wafer chuck and dusts such as particles floating in the cleaning sections also adhere to it even though they are quite small in amount. These solutions and particles contaminate it, thereby causing the wafers to be also contaminated and their electrical properties to be deteriorated accordingly. To solve this, the cleaning system has included a section for cleaning the wafer chuck. The wafer chuck is cleaned in the chuck cleaning section just before it conveys clean wafers. This is intended to convey the clean wafers by the cleaned wafer chuck.
Various kinds of chuck cleaning manner have been used. One of them is to immerse the chuck in extrapure water. The other is to jet extrapure water to the chuck. The former is intended to immerse the chuck in extrapure water in a process vessel to remove chemical solution and particles from it. The latter is intended to jet washing liquid such as extrapure water to the chuck through a plurality of jetting nozzles of paired liquid supply pipes which extend along the chuck while sandwiching it between them. Even if either of these two manners is used, however, washing solution or agent still stays in wafer holding grooves on arms of the chuck.
In a chuck cleaning apparatus disclosed in Published Unexamined Japanese Patent Application No. 61-153340, dry gas is Jetted to the chuck to dry it while blowing out washing solution still staying in the wafer holding grooves on arms of it by dry gas jetted. In this chuck cleaning apparatus, as shown in FIGS. 1 and 2 of the publication, a pair of gas supply pipes 52 are arranged on both sides of each arm 32 of the chuck, extending along the arm 32, and dry gas is horizontally jetted to the chuck through apertures of the gas supply pipes 52. When horizontal rods of each arm come side by side with the gas supply pipes 52, the chuck is stopped to dry the horizontal rods of its arm. In the case of this apparatus, however, the chuck drying speed is slow and washing solution cannot be completely removed from the horizontal rods of each arm.
Published Examined Japanese Patent Application No. 2-44522 discloses another apparatus intended to more effectively remove washing solution from the horizontal rods of arms of the wafer chuck. As shown in FIGS. 1 and 2 of the publication, this apparatus includes a pair of fixed gas nozzles 7 exclusively used for vertical rods 31a of each arm of the chuck and a pair of movable gas nozzles 10 exclusively used for horizontal rods 31b of each arm. Gas jetted through the paired movable gas nozzles 10 is directed to the horizontal rod but tilted toward an exhaust duct 40 along the horizontal rod. In this apparatus, too, the chuck cleaning speed is slow. In addition, the apparatus itsel becomes complicated.